Composite items are generally constructed from layers of material that are laminated together. These layers are often referred to as partial or full plies. For structures exceeding the available material width, each layer is typically made up of a series of strips or courses of material placed edge to edge next to each other or are overlapped to some extent. Each ply may be in the form of woven fibers in a fabric, unidirectional fiber material, metal foils, adhesive films or a variety of other conformations. Unidirectional fiber material is often termed, “tape.” The fibers may be made from any of a multitude of natural and/or “man-made” materials such as fiberglass, graphite, Kevlar®, and the like.
The courses are generally laid upon the form or tool along a “natural path” of the course material. The term “natural path” refers to the path the course material would follow when rolled out on to the surface of the tool. Deviations from the natural path are generally achieved by applying force across the width of the course material. Tape is typically more rigid than fabric and tends to resist this force to a greater extent. When the force applied exceeds the flexing capacity of the material, wrinkles or bridges form in the course material. In addition, the wider the course is, the more prone the course material is to wrinkle.
Tape courses are typically applied edge to edge. To reduce internal voids, it is generally advantageous to reduce the gap distance or tolerance between the tape courses. For example, in certain relatively high technology industries such as the aerospace industry, the gap distance may be held to 0.10″ or less. For flat or cylindrical composite items, the natural path of each course is in alignment with adjacent courses. However, for contoured items, the natural path of adjacent courses may tend to cause the courses to converge or diverge. To prevent these deviations from causing the courses to overlap or diverge in excess of the tolerance, conventional automated tape lamination machines (“ATLM”) generally utilize a relatively greater number of a relatively narrower course material. Unfortunately, utilizing narrower course material reduces lay-down rates.
Accordingly, it is desirable to provide a method and apparatus capable of overcoming the disadvantages described herein at least to some extent.